Comments

I think we should really admit that Swing is dead - it's a dead project.
I've never seen a framework that its owners dpn't fixes 6 year old simple but terrible bugs (click on the edges of a JComboBox ,e.g. its bottom-left corener)
I'm developing UIs with Swing for the past 10 years, and 2011 is my last. it became impossible to create high-end UI with that framework, and all the blame goes to Sun, who for 10 years just let it to rotten...
Try telling DefaultRowSorter to treat nulls as greater than non-nulls - impossible (a private method) - because the people who maintain this framework are not serious or having difficulties in understanding what API means.
And just dont tell me that you have the face to show your customers Nimbus L&F - if they have some style, some asthetic awareness - they'll kick out of their office.
Sad words, from a developer who loves this framework most, and hates the mediocrity of its so-called developers.

SwingWorker is good for some things, but it still is missing the simple "on-swing", "off-swing", "on-swing", "off-Swing" sequences that are common for multi-component data updates.
Please look at
http://swingutil.dev.java.net and see what the org.wonderly.swing.SyncThread class does. It provides several ways that complex GUI updates can be managed for readily with proper syncronization.
In addition, we need the Context ClassLoader to work in the EDT, so we remember it at construction, and set it in play when running code in the EDT. We also wanted to cover JAAS Subject use in the EDT as well, for more complex applications that involve security and remote code download.

Please don't use a "text config" based layout engine as a new savior to layouts! A long time ago in a galaxy far far away, I put a nice simple layer over GridbagLayout that greatly simplifies how it is used and makes it trivial to read layouts of hand typed code. Have a look at http://packer.dev.java.net for what I think should really be the new face of rectangular layouts.

Some improvements for Jdk7 ?
- Listening for real clipboard data change (currently on flavour change is detected which has limited use) ? As of now, inefficient clipboard polling running in a thread can be used to detect data change but it prove problematic for large image (imagine polling for image in clipboard if the image is large)
- global keyboard hook. Currently require JNI solution to listen for keys outside Java application.

Another critical improvement most developers will like to see in JDK7 is MIGLayout. It is a excellent layout, and I wonder why till now it is not planned for JDK7. Is it another NIH syndrome ? For Form development, MigLayout or JGoodies layout is really time-saving and indispensable , and I hope the Java desktop team really consider adding it for the sake of Java Swing/JavaFX 's future.